Hello,
we can assume the following chapters are very important. There is no verbal part in TCS aptitude test except for email writing. 1/3rd negative marking will be there.
Important topics:
Number system, Equations, Ratio and Proportion, Percentages, Profit and Loss, Time and Work, Time speed Distance, Areas and Mensuration, Averages, Permutations and Combinations, Probability, Plane geometry, Seating Arrangements, Sets, Progressions, Functions.